Numerous dispensing systems exist for blending two or more fuels during a fuel dispensing event. Such systems are used quite often in a service station environment where it is desired to dispense a plurality of different grades or octane levels of fuel products by blending at least a high octane level product with a low octane level product to create one or more mid-level octane products. Blending systems offer the potential for savings stemming from reduced storage capacity requirements both at the service station and the bulk plant level. Such systems are also used for blending diesel fuels of varying cetane content levels, gasoline/ethanol fuels of varying ethanol content levels, and diesel/biodiesel blends of varying biodiesel content levels.
Often, these dispensing systems are based on an important underlying assumption, that the octane levels (or octane, ethanol, biodiesel levels) of the fuel products in the low and high octane fuel storage tanks, or more where present, are correct. For example, it is assumed that the low octane blend component has an octane of about 86 to 87 and that the high octane component has an octane level of about 92 to 93. However, due to various issues noted below, the actual octane levels of the fuel products may differ from what is expected.
A potential problem with many fuel blending systems is that they have no provision to detect the delivery of an incorrect octane level product in either the high or low level octane blending component storage tanks. Specifically, if the low octane product and/or high octane product are of different octane levels than the assumed octane rating, it may not be possible to deliver a proper octane blend during fueling operations.
Existing fuel dispensing systems are often prone to inaccuracy issues with respect to octane blend accuracy for small transaction dispensing events. Those inaccuracies can be due to a volume of blended fuel from the previous dispensing event being maintained in the fuel hose, the volume being defined between the blend manifold and fuel nozzle, which is the dispensed on the subsequent fueling event. This is typically only an issue where the octane ratings of the fuels for the two fueling events differ from each other. For example, where the selected octane ratings are the same for both events, the actual octane level of the retained volume from the first event should match the desired octane level selected by the operator for the fuel of the second event. However, where an octane level of the fuel dispensed in the previous fueling event is lower than the desired octane rating of the fuel dispensed in the subsequent fueling event, the lower octane level of the retained volume from the first fueling event causes the octane level of the overall volume of the fuel delivered in the second fueling event to be less than desired.
The present disclosure recognizes and addresses the foregoing considerations, and others, of prior art constructions and methods.